This invention relates generally to a vehicle interior panel having an air bag door and chamber formed therein and to a method for making such a panel.
Automotive vehicles usually include an instrument panel assembly located immediately in front of the front passenger seat. Each such instrument panel assembly is configured to house various switches, instruments and accessories. Instrument panel assemblies are also known to house inflatable restraint assemblies, defroster ducts and one or more air conditioning ducts for distributing conditioned or unconditioned air to the passenger compartment through outlet vents mounted in the instrument panel.
It is also known to form air bag doors in a portion of the instrument panel substrate that overlies the air bag dispenser of an inflatable restraint assembly. In some cases, the substrate may include the xe2x80x9cfirst surfacexe2x80x9d of the trim panel, i.e., the cosmetic exterior surface that would be visible to a vehicle occupant. In other cases, the substrate may be covered by a skin with a foam in between, with the skin and foam providing a resilient protective pad type covering on the outer surfaces of the substrate.
In both first surface (i.e. substrate only) and covered (i.e. skin-foam-substrate) constructions, some provision must be made for guiding or otherwise facilitating the opening of an air bag door from the panel in which the door is formed. The air bag door in such a system opens to provide a path through which an air bag may deploy. It is desirable that whatever provision is made for this purpose includes some means for insuring that the air bag door breaks and/or tears open in a generally predictable way. To better control tearing and/or breaking, air bag doors that are formed with automotive trim or instrument panels will sometimes include regions of weakened materials, reduced thickness or scoring commonly referred to as xe2x80x9ctear guidesxe2x80x9d or xe2x80x9ctear seamsxe2x80x9d. Tear guides and seams are weakened frangible areas designed to tear and/or break when an air bag inflates and forces the door to open. Some of these systems also employ tethers and/or hinges that retain the air bag door to the instrument or trim panel after the door has torn and/or broken open.
Known methods for forming tear guides include molding, cutting, or laser scoring. Current systems also include tear guides formed in inner surfaces opposite the outer visible cosmetic surfaces of instrument panel/air bag door structures to improve the aesthetic appearance of the instrument panel by concealing the presence of the door, or alternatively in the outer cosmetic surface.
The prior art also includes methods of forming interior automotive structures such as trim panels and instrument panels that include blow molding. Such structures are formed from a parison that is extruded then clamped between opposing halves of a mold. Gas in then injected into the parison to cause the parison to conform to cavity surface contours within the opposing mold halves.
For example, U.S. Pat. No. 5,328,651 issued Jul. 12, 1994 to Gallagher et al. discloses a method for manufacturing an automobile trim component. The method includes the step of coextruding a plastic un-foamed material and foamed material into a multilayer parison. The parison is then blow molded to a desired form. After the layers cure, the article is removed from the blow mold and is sectioned into multi-layered skin halves. One skin is placed in an injection mold and core resin is injected into the injection mold and onto the skin. The resin is then compressed against the skin to produce a shell comprising a resin core layer, intermediate foam layer, and decorative outer layer.
U.S. Pat. Nos. 5,527,581 and 5,714,227 Sugawara et al. (the Sugawara et al. patents) disclose a blow-molded interior automotive structure in the form of an instrument panel core portion and a method for making such a core, respectively. According to the Sugawara et al. patents, the core is formed from a parison that is formed by first extruding the parison in a tubular shape, pinching off an open lower end of the parison using a block system, then xe2x80x9cpre-blowingxe2x80x9d the parison by injecting air into the parison. The pre-blown parison is then clamped between dies of a blow molding apparatus. The dies include contours and ridges to form the outer shape of the core to include integral air conditioning and defrost air ducts. The ridges form pinched regions in the core to close the walls of the ducts. More specifically, the pinched regions cause opposing portions of inside faces of the parison to bond together to form a plurality of hollow portions in the parison. Gas in then injected into the hollow portions of the parison by a plurality of gas feed nozzles housed in the dies to cause the hollow portions of the parison to further expand and conform to the interior die surface contours within the dies. In a separate operation, a number of the hollow portions are then opened to form structures such as inlet and outlet ports for the defrost and air conditioning ducts, a recess for holding an instrument cluster assembly and a recess forming part of a glove compartment. However, the Sugawara instrument panel core is not configured to accommodate the installation of an inflatable restraint apparatus and the deployment of an air bag from the inflatable restraint apparatus.
What is needed is an interior automotive panel having an air bag door that also includes one or more air ducts. What is also needed is a method for making such a panel.
According to the invention, a vehicle interior panel is provided that comprises an inner wall and an outer wall connected by an integral side wall. A portion of the panel comprises an air bag deployment opening at least partially defined by a tear guide. A portion of the panel comprises at least one chamber located between the inner wall and outer wall of the panel. In this manner, a interior vehicle panel is provided having both an air bag deployment opening and at least one chamber in a single panel.
According to another aspect of the invention, the vehicle interior panel is part of an instrument panel assembly.
According to another aspect of the invention, the tear guide comprises an indentation of at least one of the inner wall and outer wall extending towards the outer surface of the outer wall.
According to another aspect of the invention, the tear guide comprises at least a portion of a perimeter of an air bag door.
According to another aspect of the invention, the inner wall of the panel and the outer wall of the panel comprise a pinched region at least partially defining the air bag deployment opening or the chamber.
According to another aspect of the invention, the inner wall of the panel and the outer wall of the panel comprising the pinched region are in contact or bonded.
According to another aspect of the invention, the chamber includes an inlet opening and an outlet opening. The inlet opening receives air as part of a vehicle heating, ventilation and air-conditioning system. The outlet opening directs air towards a windshield and into a passenger compartment. The outlet opening may support a vent for directing air.
According to another aspect of the invention, a tether is configured to retain the air bag door from projecting into a vehicle passenger compartment during an air bag deployment. The tether may be attached across the tear guide, to the air bag door and a portion of the panel surrounding the air bag door.
According to another aspect of the invention, a foam is disposed on an outer surface of the outer wall of the panel and a skin is disposed on an outer surface of the foam.
According to another aspect of the invention, a method for making a vehicle interior panel is provided comprising the steps of providing a blow mold comprising at least two opposing dies. The dies are configured to form a mold cavity surface. The mold cavity surface includes a ridge configured to form a tear guide. The tear guide at least partially defines an air bag deployment opening. The dies of the blow mold are parted and a plastic material in the form of a parison is provided between the parted dies. The parison is then conformed to the mold cavity surface by injecting gas into the parison and moving the dies together. The plastic material is then allowed to cool and harden, and a panel is removed from the blow mold.
According to another aspect of the invention, the step of providing a blow mold includes providing a blow mold including a mold cavity surface configured to form a chamber in the panel.
According to another aspect of the invention, the method includes the additional steps of forming openings in the chamber and varying the thickness of the panel wall by varying the parison wall thickness.